The invention relates to a hinge between a side piece and an end piece of a frame for glasses, whereby the side piece and the end piece are parts made of wire, of which one bears a hinge body serving as a hinge axle with a coaxial, peripheral groove for receiving a bearing eye consisting of a bent end piece of the wire of which the other part is made, said bearing eye forming a peripherally open eyelet that can elastically engage the peripheral groove.
In connection with frames for glasses where the side pieces and the end piece are manufactured from a bent wire, it is known (WO 87/04806 A1) to angle off the free end of the wire of the end piece to form a hinge axle that engages a bearing eye. The latter engages an end piece of the wire of the side piece, said end piece being rolled in a screw-like manner. So that the side piece can be mounted adequately clearance-free on the hinge axle and thus secured, accordingly against a tilting movement about a transverse axis relative to the hinge axle, provision has to be made for a plurality of windings for forming the bearing eye. However, the accuracy with which such a hinge is guided cannot satisfy higher requirements in spite of said measure. Furthermore, it is hardly possible to adjust the resistance of the hinge to rotation. In addition, after the hinge axle has been inserted in the winding of the bearing eye, the end piece of the end piece wire forming the hinge axle has to be bent back against the eye of the hinge in order to axially secure the bearing eye on the hinge axle, which cannot be carried out without the use of tools.
If the hinge axle is formed not by a bent off wire end but by a hinge body that is supported by the wire forming the end piece, and which has coaxial peripheral groove for receiving the bearing eye, the latter consisting of an eyelet that is open on the peripheral side and bent from the end piece of the wire of the side piece (GB 2 281 979 A), it is possible to obtain good guiding accuracy for the hinge. However, the drawback with this known hinge is that the wire of the end piece has to be joined with the hinge body with torsional strength, on the one hand, and it is expected to form with an angled off end a rotary stop means for the end piece, on the other hand, which leads to the risk of overstressing of the hinge even if the wire of the end piece coaxially extends through the hinge body. Furthermore, the wire eyelet extending over about 270xc2x0 can exit from the peripheral groove if comparatively low force of pressure is applied to the side piece, so that the latter is detached from the end piece.
Therefore, the invention is based on the problem of designing a hinge between a side piece and an end piece of a pair of glasses of the type specified above with simple constructional means in such a way that the hinge body can be safely mounted and secured against rotation in a manner meeting higher load requirements as well.
The invention solves the problem posed in that the wire of the part supporting the hinge body has an end piece bent in the form of a hairpin and located between the branches by which the hinge body is held in a form-locked manner on both sides of the peripheral groove, and the connecting crosspiece between the two branches of said end piece grips on the outer side over the eyelet of the other part, said eyelet forming the bearing eye.
Clamping the hinge body between the two branches of a wire end piece bent in the form of a hairpin effectively secures the hinge body against rotation versus said end piece of the wire, whereby the connecting crosspiece between the two branches, said crosspiece enclosing on the outside the eyelet engaging the peripheral groove of the hinge body, represents an additional safety element preventing the eyelet forming the bearing eye from getting unintentionally released from the peripheral groove of the hinge body. Furthermore, the connecting crosspiece between the two branches can be used for limiting the angle of swivel of the hinge if the wire forming the bearing eye has a radially outwardly projecting bridge on the side of the eyelet opening on the peripheral side opposing the free end of the wire, said bridge cooperating with the connecting crosspiece of the hairpin-shaped end piece of the part supporting the hinge body, forming a rotation stop means. Following a preset angle of swivel of the side piece versus the end piece, the bridge projecting radially outwards next to the eyelet is stopped on the connecting crosspiece between the branches of the end piece bent in the form of a hairpin, so that the position of use of the side piece can be constructionally preset in a simple way with the help of said rotation stop means.
If one of the two branches of the hairpin-shaped end piece of the part supporting the hinge body has a stop means protruding against the other branch and engaging a recess of the circumferential groove on the side of the hinge body facing the connecting crosspiece, said stop means serving as a stop for the eyelet guided between said stop means and the connecting crosspiece, the hinge body is safely secured in a simple manner against displacement on the two branches of the hairpin-shaped end piece via the eyelet engaging the peripheral groove because said eyelet is retained between the connecting crosspiece and the stop means against displacement along the branches. This secures the hinge body against displacement as well, as the latter is embraced by the eyelet. Furthermore, one has to take into consideration in this connection that when the pair of glasses is handled, forces of displacement are generally transmitted via the eyelet to the hinge body.
Securing the hinge body against displacement on the branches of the end piece bent in the form of a hairpin is mainly important if the two branches of said end piece extend through the hinge body through passage openings because no additional measures are required in that case for securing the branches against displacement within the passage openings. The leg of the hairpin-shaped end piece having a free end could conceivably be bent over on the outlet side of the passage opening of the hinge body in order to prevent the latter from being pulled off from said branch, but this would require the use of a tool. More advantageous conditions for mounting the hinge body are obtained if the branches of the end piece bent in the form of a hairpin extend continuously parallel with one another. In order to fix with such a design the free end of the one branch against the other branch, the free end of the one branch may engage a blind hole of a closing piece, through which hole the other branch extends in a passage opening. This type of connection of the two branches on the side opposite the connecting crosspiece is particularly recommendable if the side part is employed as the part supporting the hinge body.